Objective: Very few studies are available to relate the final histology of excised appendix with the detailed intra-operative findings during appendectomy, both open and laparoscopic. This study was aimed to correlate the histological features of appendix specimen with the intra operative findings at open appendicectomy (OA) in a bid to determine when to change the planned procedure to include further exploration.Methods: A prospective study that observes the condition of the greater omentum (GO), the vermiform appendix and peritoneal exudates at all OA done for uncomplicated appendicitis. Histological examination of the appendices done using the H&E stain.Results: Eighty-five patients had emergency open OA, their’ ages range from 6 to 62 yrs (median = 23yrs). Histology showed 7 normal appendix (HNA), 56 acute (HAA) and 22 “non acute” appendicitis (HNAA). Negative appendicectomy rate was 8.2%. The GO was sighted more in patients with HAA than HNAA (p=0.00015) and also significantly more inflamed in the former (p=0.00028). It is not significantly inflamed in those with HNAA (p=0.945). The negative predictive value (NPV) of absent GO is 35.7% while the positive predictive value (PPV) of sighted normal GO and inflamed GO are 92.8% and 100% respectively. The PPV and NPV of presence of pus for diseased appendix are 95.8% and 9.8% respectively while those of excess fluid are 94.8% and 10.8%. The PPV and NPV of macroscopic assessment of the appendix for inflammation are 97% and 45.5% respectively giving the diagnostic accuracy of 90.6%. A significant trend of increasing probability of histologically inflamed appendix with increasing severity of macroscopic feature was seen (X2 = 004 df=1, p<0.005).Conclusion: High positive and low negative predictive values are similar for all the three parameters assessed. The macroscopic appearance of the appendix has a predictive likelihood ratio for further exploration.